The present invention relates to a method and apparatus for minimizing vehicle noise and vibration due to generator set noise and vibration.
A common problem one faces in reducing vehicle noise and vibration produced by an electrical generator set and particularly when use in a recreational vehicle (RV) is that of vehicle resonance. A generator set typically includes an engine and generator. The engine and the generator both contain rotating parts, and they are generally a major source of noise and vibrations exciting resonant responses. When generator sets are installed, the vehicles respond in many different ways depending on their material properties and geometry. These factors govern the vehicle""s structural and acoustic natural frequencies. When a generator set produces a forcing frequency that is at or near one of the vehicle""s natural frequencies, a resonant response occurs amplifying the generator set""s noise and vibration. Resonances can often account for increases in overall interior RV sound levels of 10 dB or more, and much more at individual frequencies.
In conventional generator set installations, particularly RV generator set installations, resonant behaviors are difficult to avoid in the large and varied population of vehicles. That is, even if a generator set is quiet in one vehicle, the same generator set running at the same speed may cause noise and vibration in another vehicle. Furthermore, a different generator set in the second vehicle may be perfectly acceptable since it may have different excitation frequencies than the first generator set because of different cylinder arrangement and/or speed. Thus, one generator set design, even if it is of variable speed, cannot be universally quiet in all applications or vehicles if there is no knowledge of where the vehicle natural frequencies occur. In this regard, RV builders will often switch generator sets in a given RV application rather than modify their coach to accommodate a generator set witch causes more vehicle noise and vibration.
Conventional attempts at reducing vehicle resonance include manually adjusting the generator set, varying the placement or location of the generator set within the vehicle, and even changing the RV structure itself. Attempts to provide a generator set which will minimize resonance in all vehicles, include utilizing very soft or double mounting systems so as to somewhat isolate the generator set from the vehicle.
The present invention provides a method and apparatus which minimizes vehicle noise and vibration due to generator set noise and vibration thereby allowing a single generator set design to be used in all types of RV structures.
The present invention relates to a method and apparatus for minimizing vehicle vibration and noise due to generator set vibration and noise.
One embodiment provides a generator set control system for minimizing vehicle noise and vibration due to generator set noise and vibration. The system comprises one or more sensors disposed in the vehicle, a system controller operatively connected to the sensors and including logic, and a generator set speed controller operatively connected to the generator set. The system controller receives signals from the sensors during startup and operation of the generator set and compares the signals to threshold levels stored in the system controller. The system controller correlates the signals to the generator set speeds, thereby determining which generator set speeds to avoid so as to minimize vehicle noise, vehicle vibration, or a combination of vehicle noise and vehicle vibration. The generator set speed controller controls the generator set to avoid the determined generator set speeds.
In an embodiment of the generator set control system, the sensors and the system controller are permanently mounted in the vehicle. Thus, the system may be used whenever weight characteristics or acoustic properties of the vehicle change.
In another embodiment of the generator set control system, the threshold level may be altered by the operator to select a tolerable level of vehicle noise, vehicle vibration, or a combination of vehicle noise and vehicle vibration.
Another embodiment provides a method for minimizing vehicle noise and vehicle vibration due to generator set noise and vibration. The method comprises measuring vehicle noise and/or vehicle vibration at one or more locations in the vehicle during startup of the generator set, determining which generator set speeds to avoid by comparing the vehicle noise and/or vehicle vibration to threshold levels and correlating the noise and vibration to the generator set speeds during startup, and controlling the generator set to avoid the determined generator set speeds.
In an embodiment of the method, the measurement of vehicle noise and/or vehicle vibration and the comparison to threshold levels is used to control generator sets in other vehicles of the same model to avoid the determined generator set speeds.
In an embodiment of the method, the measuring of vehicle noise and/or vehicle vibration and determining which generator set speeds to avoid is performed every time the generator set is operated, to minimize vehicle noise and/or vehicle vibration in relation to the vehicle""s present weight and acoustic characteristics.
Another embodiment of the method provides a method for minimizing vehicle resonance due to generator set noise and vibration where vehicle noise and/or vehicle vibration are measured when a generator set is operated at one generator set speed for a period of time. The frequencies where average vehicle noise and/or average vehicle vibration is higher than stored threshold levels are identified and the frequencies are correlated to generator set speeds. The generator set is then controlled to avoid at least some of the generator set speeds, whereby upon subsequent startups and operation of the generator set, vehicle noise and/or vehicle vibration, caused by vehicle resonance, for example, is minimized.
It is an advantage of one embodiment that vehicle noise and/or vehicle vibration may be minimized by avoiding particular generator set speeds. A permanently mounted embodiment has the advantage that the threshold levels may be altered at will, and furthermore that the generator set may be set to avoid different speeds as the structural and acoustic properties of the vehicle change.
These and various other advantages and features of novelty which characterize the present invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the present invention, its advantages, and other objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to the accompanying descriptive matter, in which preferred embodiments of the present invention are illustrated and described.